The purpose of this thesis was to present the correlation between the grammar rules on the use of German prepositions an and auf and the cognitive perspective of their use in various contexts. The results are gained through an online survey and analyzed in the thesis. Only the semantic side of the prepositions was taken into account, along with the principles of cognitive linguistics and cognitive grammar. The thesis also shows the comparison with the generally accepted Croatian equivalent, the preposition na. The results of the analysis showed that the respondents were strongly influenced by the grammar and that it had a clear influence on their cognitive perspective, which is why the consensus among the answers and explanations was high. Although there were always some slight differences between the answers and explanations, the real difference was visible only in the analysis of more abstract examples or those that represented the very similar use of the two prepositions.